pbulk using tmpfs

Hi,
I'm running bulk builds for various archs using pbulk for quite
some time now, and one of the domUs used for this is hosted by
a server with a LSI MPT Fusion Raid controller. In short, that
controller sucks, poor write performances, it is a well known
fact. In order to speed up builds, I would like to know if I
could benefit from tmpfs by mounting the WRKOBJDIR as a tmpfs
directory.
In particular, while most packages will fit into a couple of
megabytes, some of them (firefox, libreoffice, openoffice,
koffice and such) take a couple of gigabytes to get built.
My question is: how will tmpfs behave? If I mount the WRKOBJDIR
without any argument, it will "use", if I understand correctly
the manpage, all of the available memory. Does this mean I will
end up in a situation were the system memory will be filled by
the build or is there some kind of smart mechanism within tmpfs
which will "overflow" somewhere?
Thanks,
------------------------------------------------------------------
Emile "iMil" Heitor .°. <imil@{home.imil.net,NetBSD.org,gcu.info}>
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